We propose to study the binding of growth hormone to isolated target cells and target cell membranes of normal and pathological tissue. These studies will be pursued to the isolation from target cell membranes of a specific protein complex which binds growth hormone. This receptor complex will be characterized physically, chemically and biologically. A correlation will be made between the binding of growth hormone, using radioiodinated growth hormone, to target cell membranes and physico-chemical changes in these membranes. This latter approach will use spectroscopic techniques i.e. circular dichroism, spectrofluorescence and nanosecond decay time fluorescence. Since several populations of plasma membranes have been obtained, these will be characterized chemically and physically. In addition to binding of peptide hormines and lectins, the responsiveness of these membrane fractions to peptide hormones and lectins will be studied spectroscopically and enzymatically. Growth hormone binding to normal and transformed human lymphocytes will be compared to insulin and lectin binding to these cells. Lymphocytes from patients with lymphocytic leukemias and sarcomas as well as immunologically deficient and endocrinopathic patients will be tested. Similar studies will be done with isolated normal and hepatomatous liver cells.